Means and method for inspecting inner surfaces of tubular members



G. L. c DEHN ET AL. 2,682,032

June 22, 1954 FOR INSPECTING INNER. I SURFACES OF TUBULAR MEMBERS MEANS AND METHOD Filed March 8, 1950 12am Karena-m2 Patented June 22, 1954 UNITED STATES QFFICE MEANS AND METHOD FOR IN SPECTING INNER SURFACES 0F TUBULAR MEM- BERS George L. C. Dehn, Dallas, and William H. Crenshaw, Midland,

Tex., assignors to Magnaflux 12 Claims. 1

The present invention relates to means and a method for inspecting inner surfaces of tubular members. More particularly, the present invention relates to apparatus for the non-destructive, magnetic particle inspection of the interior surfaces of tubular members and to a method of inspecting said surfaces.

The principles of non-destructive, magnetic particle inspection for magnetizable members are well known. However, no entirely'satisfactory method or apparatus employing these principles has heretofore been provided for efliciently inspecting the interior surfaces of a tubular member. The present invention now proposes a sim ple, inexpensive, easily employed apparatus and method whereby said testing may be carried out in an efficient, substantially fool-proof manner.

The apparatus of the present invention includes a magnetizing head of less diameter than the inner diameter of the tubular member to be inspected, so that the head can be readily inserted into the bore of the member. The'head carries means for setting up a magnetic field with the lines of flux extending longitudinally of the wall surfaces of the tubular member. As is well known, the setting up of such a magnetic field will cause a definite orientation of the magnetizable particles about any flaws or surface discontinuities in the object to which the field is applied, in the tubular member.

In order to observe this particle orientation, viewing means are provided by the apparatus of the present invention. These viewing means include a telescopic type viewer secured to the head and insertable therewith into the bore of the member being tested. The telescopic viewer extends through the bore of the member being tested with the eye piece of the viewer projecting from the bore. A light source is preferably carriecl by the head for illuminating the inner surfaces of the member being tested and reflective means are also carried by the head to reflect light from the inner surfaces of the member axially of the member through the telescopic viewing means so that particle orientation upon the surfaces may be readily viewed.

The method of the present invention includes the steps of applying to the inner surface of a tubular member a magnetizable material, preferably in the form of finely divided ferromagnetic particles having visual characteristics differing from those of the member being tested, magnetizing the wall surface of the member to obtain magnetic orientation of the material about present instance, in the any flaws present in the surface, and the visual inspection of the inner wall surface to determine the position and nature of such orientation, The first two steps of this method may be carried out in either order.

It will thus be seen that the present invention provides both apparatus and method for the inspection of inner wall surface of a tubular member and the location of flaws present therein.

It is, therefore, an important object of the present invention to provide means for the inspection of inner wall surfaces of tubular members.

Another important object of the present invention is to provide an improved method for the magnetic inspection of the inner wall surface of a tubular member.

It is a further important object of the present invention to provide apparatus for the inspection of the interior wall surface of a tubular member, including means for magnetizing the inner wall surface of the member to cause an orientation of magnetizable particles applied thereto and means for visually inspecting the inner wall surface from a remote point to determine the position and nature of such orientation.

Still another important object of the present invention is to provide a method for the magnetic particle inspection of inner wall surface of tubular members including the steps of applying magnetizable particles to the inner wall surface, magnetizing the wall surfaces to cause the magnetic particles to build up at the locations of any flaws present therein, and the visual inspection of inner wall surface to observe the pat tern assumed by such magnetic particles, the first two steps being carried out in either order.

Other and further important objects of the present invention will be apparent from the disclosures in the specification and the accompanying drawings.

On the drawings:

Figure 1 is a longitudinal, sectional view, partly in elevation, through the axis of a tubular member with apparatus of the present invention positioned therein;

Figure 2 is an enlarged sectional view taken along the plane H-II of Figure l Figure 3 is a view similar to Figure 1 showing the positioning of a modified form of apparatus of the present invention within a tubular member; and

Figure 4 is an enlarged sectional view taken along the plane IV-IV of Figure 3.

pair of spaced, generally circular disks l3 and- Hi of a diameter less than the interior diameter of the member ID joined by aplurality of supporting tubes or rods extending axially of the member (0 within the bore thereof. An additional disk It is secured in spacedrelationtocthe :dlSkl3 by means of a generallycylindrical collar or" 1 other joining element H of lesser diameter than the disk. The head l2 carries a .pair of.-electromagnetic coils l8 and 19, one of the coils, namely the coil l8, being secured about the collar ll between the disks l3 and it, and the other coil,

namely the coil [9,abutting-the diskill andsurrounding a tubular member-'20 extending axia-llyof the tubular member- H} fromthe disk I4.

A light source, such-as a bulb 2 l, is-secured to the disk l3 by suitable means, as by a socket 22,-

the bulb 2| extending from the disk 13 to lie between the. disks-l3 and M A'mirror 23 is secured" to the disk 14 by means of-an-angle arm 24, the mirror extending into closelyspaced relation to the light source 2| andbeing inclined at an angle, preferably on the orderof 45, to the-axis of the head l2 and the tubularmember ill.

The telescopic viewin means, indicated genorallyat. .25, are provided for viewing the: inner surfaces of the tubular .member 10.: I'he telescopic :viewing means -25 :includes the tubular member extending axially ,throughvthecoili9" andsecured-to the-disk l4 of the head 12 as hereinbefore I described; A full vision objective .lens

is mounted inside -the tube 20 adjacent that end of the tube 20 secured to the disknlL-which is centrallywapertured at 21 so that the image of the innersurfa'ce oh-the tubular member; as .re-" flected'by the mirror.- 23,:may ,be transmitted. by

the lens-26.. Apluralitypf fixednesting tubular members 28 and 29 are-provided to extend beyond the confines of the;-tubular member 10, and light from thesource 2l is-transmittedaxially through the members 28 and 29, inimuch-the same man:-

ner as anordinary (optical telescope by. means of." other lensesflD-iand 31 mounted in the-tubes 28 and 29. An eyepiece 32 witha'lens 33' is positioned at the'viewing end of: the terminal telescopinglmemb'er 29. The lens ratio of the. lenses f 26; 38,31: and His-preferably. one-to one so that" the image viewed-through the telescopic viewing means. 25 is not enlarged but is merely transmit ted from theheadl 2 to the; eye piece lens 331.. Iiiasmuch:asethe 'objective lens26 :is of the. full View type, .it covers a sufiicient angle so that theentire inner circumference of the members! 0 may be viewed obliquely at one time, and-it isnecessaryto usethe mirror 23 onlywhenit is desired to examine closelya relatively small area of. the

surface Illa. In order to facilitate movement of the apparatus l l axially through the bore of the tubular member In, a pluralityof cantilever-type leaf springs 34' "are mounted "upon the periphery of the disk M to provide sliding contact With'th inner wall surfaces lOa-of'the tubular member [0. Electrical power is provided for the light source 2 land the electromagnetic coils l8 and I!) through a conduit 35 extending along the length' of the bore ofthe tube H1.- The conduit carrying power to the bulb 2| and the electromagnetic coil I8 may desirably extend through one of the tubular supporting members [5 of the head [2 as shown in Figure 2.

The operation of the device of Figure 1 will be evident-to those; skilled inithe artz'i The interior surfaces 10a of the tubular. member. ID "are coated with magnetizable material, preferably in the form of finely divided particles. These particles preferably possess optical characteristics differin from those of the interior surfaces IBa, either by reason: of thecinherent color of the particles, because of a dye applied to the particles, or because of fluorescentzmaterial applied thereto. In case fluorescent material is employed, the light source-2 I: is preferably capable of emitting ultraviolet. lighter. other exciting illumination.

According to one embodiment of the method of the. present invention, the inspection material is initially applied to the interior surface Illa, and thewdevice H- is insertedwinto:thebore ofwthe member ID ;and -is. moved progressively therealong-with-the:eyepiece 32. projecting from the end of v the member- IO: The interior surfaces Illa .are 'illuminatedsby thelight source 2! and may the readily. viewed through the telescoping The spring supports -34 serve viewing means 25. to center therappa-ratusil withinthe bore being inspected while the electromagnetic coil i8, energizedthrough'theconduit ,will'set upa mag-a neticfield within the'wallsuof the tubular =mcmher it) and particularly lengthwise of I the inner. surface 4 Illa-thereof... 'I'he-electrical power.- sup- 0 pliedto the coils .I8and: l9-may be A. 0., D. C.,

puIsatingHDN-C or halfwave currenth In any. case, the particles of: magnetizable vmaterial which are presenton thesurface lfla will orient themselves with v respect to 1 any flaws present: in the surfaces, and the particle orientation may :be readilyviewed within the section of" the tube illuminated-bythelight source. 2 I by merely lookinguthrough the .eye piece -32 and the viewing.- Inlorder :toinspect closely all of the surface [0a, as whemthe mirror 23 is utilized, the device-1| lmaygbe-rotatedi as. it is .-moved.

means 25.

through .thebore.

Alternatively, the :device .1 i may. -be:-. initially passed through themember .10 prior to the appli-. cationof magnetizable material tothe surfaces lOa-to set upa-magnetic field as above described Next, finely divided magnetic materialmay be applied to the. inner. surfaces llia ras by blowing powdered-.matei:ialminto .oneendof. tha -bore of the member! (Land the Viewer I isagain passed;-

through the bore of the member. l0,-. preferably withthe coils IB and .IS deenergizedr Thus, any. defects. in the surfaces lflwcan be observed by the orientation ofethe magnetic particles uncles theinfluence of .residualrmagnetism.

In the embodiment. ofv the present invention. illustrated in. Figure 3, reference numeral Hi again refers tora tubularv member formed iof.

magnetizable" material and reference numeral 40 refers generally to a modified formof device as.

shownin Flgure'l." The. device 40 includes a plurality of disks 4l',42 and 43 spaced axially oflthe bore 10s, the disksbeing'similar. to the disks"i3,."

M and I6 of the embodiment of Figure 1. Disk 41 carries spring supporting means 4 similar to the means '34 of Figure 1 while a pair of spaced electromagnetic coils'lllii and 46, similar to the coilsl8andil9 of: Figure 1, are carried'by the" disks 4! and "42,. respectively, the. disks" being maintained in spaced apart "relation bytubular supporting means .:4 1

A generally frusto-conical deflecting plate 618 is supported upon the tubes 4'! passing therethrough adjacent to the plate periphery and a nozzle 49 having an enlarged outlet mouth 59 is likewise supported by the tubes 4! in closely spaced relation to the deflector plate 58. The nozzle 49 communicates through a conduit 5i with a source of powder or finely particulated magnetizable material for a purpose to be hereinafter fully explained. The plate 42* also carries a lamp socket 52 and a lamp 53 extending axially of the bore away from the coil es, the socket 232 and the lamp 53 being similar to the socket a? and lamp 2! of Figure 1. The disk 43 is supported in spaced relation to the disk 42 by means of hollow rods or tubes 54 which may also serve to carry an electrical conduit 55 supplying energy to the coils 45 and 48 and the lamp 53. A mirror 55 is supported in spaced relation to the plate 43 by means of the supporting arm 51, the mirror 56 being closely adjacent to the light source or bulb 53. The reference numeral 58 refers to a tubular member similar to the member N. of Figure 1 constituting a portion of a viewing means similar to the means 25 of Figure 1 and hereinbefore described in detail.

The operation of the modified form of the device illustrated in Figures 3 and l will be evident to those skilled in the art from the foregoing description. However, in this instance the device 4c is inserted into the bore 18a prior to the application of magnetic material thereto, thus eliminating the separate step of previously trea ing the bore of the member I 0 with magnetizable material. Magnetic material, preferably in the form of powdered or finely divided magnetizable particles suspended in a fluid stream, is blown into the bore l Ea through the conduit 53 and the nozzle 49, the material emanating from the enlarged exit mouth 50 being deflected outwardly into contact with the surfaces Illa by means of deflector plate 48. The particles from the plate 48 pass through the magnetic field set up by the electromagnetic coils 45 and it, this field also being present in and on the surface of the walls of the tubular member ID. The magnetic particles thus are subjected to the magnetic field and orientate themselves upon the surfaces 580: about any flaws present therein.

This orientation of magnetic material may be viewed by means of a telescopic viewers, as described in connection with Figure l, the interior surface Illa being illuminated by light or exciting illumination emitted by the source 53 and refiected into the tubular member 58 either directly or by means of the mirror 56. Although the viewing means, namely the mirror 56, the tubular member 58 and the light source 53, are not in the magnetic field proper, the wall surfaces Hla will retain sufficient residual magnetism to tain the particles in their oriented condition until after they have been viewed as hereinbefore de scribed.

The method of the present invention will be appreciated from the disclosure of the apparatus as hereinbefore described. The method includes the application of magnetizable material to the wall surface 10a, orientation of the magnetic material by means of the magnetic field set up by the operation of the coils lB--i9 or 45-46, and e this magnetic material orientation may be readily viewed visually, as by the means herein set forth.

It will be noted that the spring mounting means 34 and 44 will not interfere with the oriented pattern assumed by the magnetizable material within said tubular member relatively thereto present upon the surfaces [0a. In the case of the first embodiment of the invention, the springs contact the inner surfaces Hla at a point rearwardly of that being viewed through the mirror 23, while in the embodiment of Figure 3 the springs 44 contact the walls la in advance of the magnetic field ahead of the point at which the magnetic material is applied to the surface We.

It will also be appreciated that the apparatus I I can be inserted into either end of the tubular member it! so that a member having an axial length twice that of the apparatus may be inspected by inserting the apparatus in one end of the tubular member to inspect one-half of the bore of the member and then inserting the apparatus in the other end of the member to complete the inspection.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. Apparatus for magnetically inspecting the inner surface of a tubular member, comprising a head insertable into said member, means carried by said head for magnetizing said inner surface.

telescopic viewing means secured to said head and of such length as to project from the tubular member as said head is moved lengthwise and light reflective means carried by said head and positioned in proximity to said magnetizing means to reflect light from the inner surfaces of said member into said viewing means.

2. Apparatus for magnetically inspecting the inner surface of a tubular member to which ferromagnetic particles have been applied, com prising an elongated head insertable into said member, a pair of spaced electromagnetic coils carried by said head, means for supplying electric current to said coils to energize the same and set up a magnetic field therebetween so that said particles will orient themselves about flaws in said wall surfaces, a light source carried by said head in close proximity to said coils, and telescopic viewing means of such length as to project from said head beyond the confines of the tubular member as said head is inserted axially into said member, said telescopic viewing means being constructed and arranged to. receive light reflected from the inner surface of said tubular member, whereby orientation of said magnetized particles upon said surface may be viewed through said viewing means and the pres ence of flaws in said surface may be detected.

3. Apparatus for magnetically inspecting the inner surface of a tubular member to which-ferromagnetic particles have been applied, comprising a head insertable within said member, a pair of spaced electromagnetic coils carried by said head, means for supplying electric current to said coils to energize the same and set up a magnetic field therebetween so that said particles will become oriented on said surface, a light source carried by said head and interposed between said coils, and viewing means also carried by said head for transmitting light axially along the length of said member.

4. Apparatus for magnetically inspecting the inner surface of a tubular member to which ferromagnetic particles have been applied, comprising anelongated headinsertable into said member, electromagnetic elements carried by said head and spaced axially of i said member upon inser tion of the head therei-nto, means for supplying electric current to saidelernents to energize-"thev same and thus'set upaunagnetic field therebe tween'so that said particles Wi-11 become oriented on said'surface; telescoping viewing means of such length as to project axially from said tubular member ;as the head is inserted thereinto,-and a light source"positionedsbetween said elements to illuminate-said, inner surfaceand said -particles present :thereon, whereby orientation of said particles upon said surface may be observed through said viewing means.

5. Apparatus: for magnetically inspecting the inner surfaceof-a tubular member to which ferromagnetic particles have been applied, comp-rising an elongated head-insertable' intosaid member, a pair of spaced electromagnetic coils carriedby said head, means for supplyingelectric current to said coils to energize the same and thus set up a magnetic field therebetween including said par ticles, resilient meansicarried by-said head for centering said head Within said member, a light source carried by said head and interposed between said coils, and-viewing means secured to said head-and of such length as to extend beyond the confines of said member as said head is moved lengthwise within said'tubular member to trans mit an image of saidmagnetized particles to a position without said member.

6. Apparatus for magnetically inspecting the inner surface of a tubular member, comprising a head insertable withinsaid member for axialmovem'entthrough said member, a pair of spaced magnetic coils carried'by said head, a deflector plate carriedby said'headand located between said coils, a'nozzle for connection toasource of powdered ferromagnetic material for discharging said material under fiuid'pressure against deflector plate; and a light source ca rice. by

said head rearwardlyzof said-'coils,-whereby the pattern assumed bymagnetized particles upon the'inner wall'surfaces of-saidmembers due to residual magnetism-in said member may be ob served byv means or illumination from said light source followingsaid coils assaidhead is moved through said members 7. The methodof inspecting the interior surface of a tubular: member whichicomprises mag-- netizing said member lengthwise thereof blowing finely particulate'd:magnetic particle under air 1". assure into saidtubular member, and progressively reflecting and visually observing the reflected image of the pattern assumed said particles along successive increments of'said-interior surface while the particles are subject tosaid magnetization, whereby the entire tubular 1nemoer is progressively inspected'in successive incl-e ments therealong said magnetization.

8. The method of inspecting-the interior sur face of atubular member 'which'comprises progressively magnetizing saidumember lengthwise thereof, blowing under-air pressure a-stream of powdered magnetic'material onto the magnetized inner surfaceof said tubular member, and progressively reflecting-and visually observing the image of the-pattern assumed-bysaid'particles along successive increments of said innersurface under'the' influence-of -suchmagnetization to detect the presence of surface defects therein whereby the entire tubular member is :progressively inspected in successive increments.

9. The method of inspecting the interior surface of a tubular membcn which comprises applying magnetizable particles-to said=inner surface of said member, progressively magnetizing increments along said member, and 'progressively-refleeting and visually, observing the reflected image of the orientation of said particles on said increments along said. member contemporane ously with the magnetization ofsaid increments, whereby magnetization and observation take place progressively through the tubular member. 10. The method of inspectingtheinterior sur-. face of a tubular member which comprises magnetizing a portion ;of the interior surface of' said member, contemporaneously applyingfinely particulated magnetic particlesto the magnetized portion of said member, and contemporaneously with the magnetizing of said portion of the 1111-. bular surface observing. the reflected image of the pattern assumed by said particles onvsaid portion of the interior. surface of said tubular member.

11. Apparatus for inspecting the inner surface of a tubular member,zcomprising a-headinsertable into said member, viewing means connected to said head and of such length as to project' from the tubular member as said headis moved within said tubular member, means for magnetizing a portion of the inner surface of said tubu iar member, means carried by said head for delivering ferromagnetic. particles onto said magnetized portion of said tubular member inner surface, and light reflective means carried by said head for reflecting light from said magne tized portion of saidtubula'r member inner surface into said viewing. means to. indicate any. flaws therein;

12. Apparatus for magnetically inspecting the inner surface of "a tubular member, comprising an assembly insertable into saidmember including viewing means of such length-as to project from the tubular member beyond the confines of the tubular member as the assemblyis moved axially into said member, illuminating means carried by said assembly for illuminating the interior of said member, said viewing means being constructed and arranged to receive light reflected from the inner surface of said tubular member, and means including a conduit terminating in proximity tosaid illuminating means and carried by said assembly for delivering ferromagnetic particles to the inner surface of said tubular member; whereby when the surface is magnetized, the orientation of said particles upon said surface may be viewed through said viewing means to observe any flaws therein.

References Cited in the file of this patent. UNITED STATES PATENTS Number Name Date 1,947,729 Morrison Feb. 20; 1934 2,124,579 Knerr et a1. July 26;1938 2,216,600 Moore Oct. 1, 1940 2,251,739 Huntsinger Aug.- 5, 1941 2,371,176 Kirk et a1; Mar;13,-1945- 2,495,545 Peterson et al Jan. 2i,1950 2,587,476" Huhn Feb. 26,1952

FOREIGN PATENTS Number Country Date 547,714 Great Britain Sept. 8,1942 

